The field of this invention is micro-fluidic devices.
Carrying out chemical or biochemical analyses, syntheses or preparations, even at the simplest levels, requires one to perform a large number of separate manipulations on the material components of that analysis, synthesis or preparation, where such manipulations include, but are not limited to: measuring, aliquoting, transferring, diluting, concentrating, separating, detecting, etc. One step that is performed in many of the above described processes is the separation of one or more components from a multi-component fluid sample. Such separation steps are common in applications where a given sample is concentrated with respect to one or more of its constituents and/or xe2x80x9cdesalted.xe2x80x9d
In many situations, it is desirable to work with small volumes of fluid, e.g., from femtoliter to xcexcl quantities of fluid. Such situations include sample analysis in which small volumes of initial sample are analyzed; chemical synthesis, in which small quantities of chemical are desired and/or expensive reagents are employed; and the like. As such, there has been much interest in the development of micro-fluidic devices in which fluid is manipulated through one or more micro-channels present in the device.
Many of the above described manipulations easily lend themselves to such miniaturization and integration. For example, the use of these microfluidic technologies has been described in a number of applications, including, e.g., amplification (U.S. Pat. Nos. 5,587,128 and 5,498,392) and separation of nucleic acids (Woolley et al., Proc. Nat""l. Acad. Sci. 91:11348-352 (1994) and hybridization analyses (WO 97/02357 to Anderson).
However, not all of the above described manipulations have been successfully adapted to be carried out in a microfluidic device. One type of application that has not yet had great success in the microfluidic setting is the separation of components from a multi-component sample. While protocols have been developed or suggested to both concentrate and desalt a sample in a microfluidic device, these technologies are not entirely satisfactory for a number of reasons, e.g., unsuitability for use with a wide range of fluid samples, difficulty in fabrication of the microfluidic device, etc.
As such, there is great interest in the development of a technology that can easily and reliably perform sample separations in a microfluidic format. The present invention satisfies this need.
Relevant Literature
References of interest include: U.S. Pat. No. 5,869,004; as well as Matson et al., SPIE (1998) 3519:200; F. Xiang et al, Anal. Chem. (1999) 71:1485Feil et al., J. Membrane Sci. (1991) 64:283.
Micro-fluidic devices are described in U.S. Pat. Nos. 5,770,029; 5,755,942; 5,746,901; 5,681,751; 5,658,413; 5,653,939; 5,653,859; 5,645,702; 5,605,662; 5,571,410; 5,543,838; 5,480,614, the disclosures of which are herein incorporated by reference.
Reversible gel compositions are described in U.S. Pat. Nos.: 5,720,717; 5,672,656; 5,631,337; 5,569,364; 5,670,480; 5,658,981; 5,470,445; 5,432,245; 5,298,260; 5,162,582; 4,439,966, the disclosures of which are herein incorporated by reference.
Methods for selectively separating at least one component from a multi-component fluidic sample are provided. In the subject methods, the fluidic sample is introduced into a micro-fluidic device that includes at least one micro-valve made up of a phase reversible material. The multi-component fluidic sample is then contacted with the microvalve in the microfluidic device under conditions sufficient for the at least one component to enter, and often pass through, the microvalve, while the remaining constituents of the fluidic sample remain outside of the microvalve. Also provided are kits for use in practicing the subject methods, where the kits include at least a microfluidic device having a microvalve and instructional material, or at least means for obtaining the same, on how to use the device in the subject methods. The subject devices find use in a variety of applications, including sample desalting and concentration applications.